Alterations in synaptic vesicle storage function during induced recycling are studied in electroplaque synapses of Narcine brasiliensis. The nerve are stimulated to generate two classes of transmitter-depleted vesicles; a) minimally recycled, active vesicles, and b) maximally recycled, functionally demobilized vesicles.. Uptake of ACh by isolated vesicles is investigated in order to establish the mechanism and kinetic parameters of this process first in active vesicles, and then to determine changes in uptake capability of the demobilized vesicles. Concurrently with biochemical studies, recycling of vesicles in intact terminals is being investigated ultrastructurally employing extracellular tracers, primarily dextrans.